CA1309769C - Dual polarization electromagnetic power reception and conversion system - Google Patents
Dual polarization electromagnetic power reception and conversion systemInfo
- Publication number
- CA1309769C CA1309769C CA000577680A CA577680A CA1309769C CA 1309769 C CA1309769 C CA 1309769C CA 000577680 A CA000577680 A CA 000577680A CA 577680 A CA577680 A CA 577680A CA 1309769 C CA1309769 C CA 1309769C
- Authority
- CA
- Canada
- Prior art keywords
- rectennae
- rectenna
- reception
- electromagnetic waves
- lines
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/40—Circuit arrangements or systems for wireless supply or distribution of electric power using two or more transmitting or receiving devices
- H02J50/402—Circuit arrangements or systems for wireless supply or distribution of electric power using two or more transmitting or receiving devices the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/12—Supports; Mounting means
- H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
- H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
- H01Q1/248—Supports; Mounting means by structural association with other equipment or articles with receiving set provided with an AC/DC converting device, e.g. rectennas
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
- H01Q21/061—Two dimensional planar arrays
- H01Q21/062—Two dimensional planar arrays using dipole aerials
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
- H01Q25/001—Crossed polarisation dual antennas
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/20—Circuit arrangements or systems for wireless supply or distribution of electric power using microwaves or radio frequency waves
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/20—Circuit arrangements or systems for wireless supply or distribution of electric power using microwaves or radio frequency waves
- H02J50/27—Circuit arrangements or systems for wireless supply or distribution of electric power using microwaves or radio frequency waves characterised by the type of receiving antennas, e.g. rectennas
Abstract
ABSTRACT
An antenna array for receiving dual polarized electromagnetic waves, comprised of a first thin-film printed circuit rectenna having a plurality of linear half-wavelength dipole antennae oriented in a first direction for receiving a first component of the dual polarized waves, and a second thin-film printed circuit rectenna parallel to the first rectenna, having a plurality of linear half-wavelength dipole antennae oriented in a second direction for receiving the second orthogonal component of the electromagnetic waves. A reflector screen is disposed parallel and behind the second rectenna, for reflecting incident electromagnetic waves transmitted through the first and second rectennae back to the first and second rectennae for reception thereby. The dipole antennae of the first rectenna are disposed in a predetermined pattern in relation to the second rectenna dipole antennae, the first and second rectennae are separated by one of either substantially zero distance or by a multiple half-wavelength distance, and the second rectenna and reflector screen are separated by a predetermined distance to effect substantial cancellation of transmission line shielding effects and mutual coupling, resulting in high efficiency signal reception.
An antenna array for receiving dual polarized electromagnetic waves, comprised of a first thin-film printed circuit rectenna having a plurality of linear half-wavelength dipole antennae oriented in a first direction for receiving a first component of the dual polarized waves, and a second thin-film printed circuit rectenna parallel to the first rectenna, having a plurality of linear half-wavelength dipole antennae oriented in a second direction for receiving the second orthogonal component of the electromagnetic waves. A reflector screen is disposed parallel and behind the second rectenna, for reflecting incident electromagnetic waves transmitted through the first and second rectennae back to the first and second rectennae for reception thereby. The dipole antennae of the first rectenna are disposed in a predetermined pattern in relation to the second rectenna dipole antennae, the first and second rectennae are separated by one of either substantially zero distance or by a multiple half-wavelength distance, and the second rectenna and reflector screen are separated by a predetermined distance to effect substantial cancellation of transmission line shielding effects and mutual coupling, resulting in high efficiency signal reception.
Description
02 n\CKODOU~D o~ ~] ~V~ OW
03 This invention relates in general to the 04 transfer of electrical power between two separated 05 locations by means of transmitting and receiving 06 electromagnetic waves, and more particularly to an 07 antenna array for receiving dual polarized electro-08 magnetic waves with high efficiency over a wide range 09 of angles of incidence.
Research in the area of remotely powered 11 mobile systems has centered around the requirement for12 cost effective means to receive and convert 13 transmitted electromagnetic power into direct current 14 power when the transmitter and receiver are moving relative to one another.
16 For example, it has been proposed that an 17 electromagnetic power recep-tion and conversion system18 could be implemented for transmitting propulsive and 19 communications payload power in the 2.4 - 2.5 GHz microwave ISM band to a lightweight electrically-21 powered aircraft circling over a fixed ground antenna 22 system for continuous periods of weeks or even months 23 at a time.
24 One prior art electromagnetic power reception and conversion system is described in U.S.
26 Patent 3,434,678, and is referred to as a linear 27 rectenna. This device consists of an array of 28 linearly polarized half-wavelength dipole antennae, 29 each followed by a conversion system consisting of wave filters and rectifier circuits.
31 In order to achieve high efficiency power 32 collection with the linearly polarized rectenna 33 described in the prior art patent, the transmitted 34 electromagnetic field must itself be linearly polarized. In addition, the polarization orientation 36 of this field must be maintained parallel to that of 37 the rectenna dipoles, or vice versa, in response to 38 changes in the orientation of the receiving rectenna ~' - .
1 30q76q 02 relative to the power transmission antenna, or due to 03 Faraday rotation of a polarized beam transmitted 04 through the ionosphere, etc. In other words, 05 expensive and complex polarization tracking equipment 06 must be provided at either the transmitting antenna or 07 the receiving rectenna in order for the system to 08 operate properly with high efEiciency power 09 collection.
An improvement in linearly polarized 11 rectennae is described in an article entitled "Design 12 Definition of a Microwave Power Reception and 13 Conversion System for Use on a High Altitude Powered 14 Platform" NASA/CR/156866, by W.C. ~rown, published in 1981. According to the Brown article, a linearly 16 polariæed rectenna is disclosed in the form of a 17 thin-film printed circuit. This type of linear 18 rectenna has many desirable characteristics which were 19 not possessed by earlier prior art rectennae constructed of discrete components; such as those 21 described in a further article of W.C. srown entitled 22 "The History Of The Development Of The ~ectenna", 23 publication of the S.P.S. Microwave Systems Workshop, 24 Rectenna Session, Lyndon B. Johnson Space Center, Houston, Texas, January 15-18, 1980.
26 With the exception of the inclusion of 27 rectifier diodes, all components of the improved 28 rectenna were etched on a sing]e thin-film dielectric 29 sheet. Therefore, when compared with earlier discrete component rectennae, the potential fabrication costs 31 for volume production are very low. Furthermore, the 32 structural weight of the thin-film rectenna is very 33 low (eg. typically less than 100 grams-per-square-34 meter), and the thin-film fabrication is very flexible and can be conformed to curved surfaces such as 36 aircraft wings, etc.
37 However, the improved rectenna disclosed by 38 W.C. Brown also suffers from the principle 1 3aq76s 01 ~ 3 ~
02 disadvantage oE well known prior art discrete 03 componen-t rectennae, which is that for high efficiency 04 power reception the polarization orientation of the 05 field should be parallel to that of the rectenna 06 dipoles, resulting in the necessity of expensive and 07 complex polarization tracking equipment.
08 A further prior art system is described in Og U.S. Patent 3,681,769 which teaches the use of multiple phased arrays of orthogonal dipoles disposed 11 on separate planes and interconnected via transmission 12 lines for transmission of radio signals in a dual 13 polarized beam.
14 However, this prior art approach suffers lS from poor efficiency performance due to shielding 16 effects caused by the transmission lines. As an 17 example, when two thin-film rectennae of the type and 18 dimensions described in the latter mentioned article 19 by Brown are laid out in two orthogonal foreplanes as taught by U.S. Patent 3,681,769, it can be readily 21 shown that approximately 30-40~ of the power in one 22 polarization is prevented from being received by the 23 transmission lines of the other foreplane.
24 Furthermore, such phased arrays of orthogonally disposed dipoles are subject to extremely poor 26 directivity when applied to systems in which the angle 27 of beam incidence varies (e.g. in systems 28 characterized by relative movement between the 29 transmitting and receiving stations, such as in an electrically propelled airborne transportation 31 system). This is because the directivity of such 32 arrays is proportional to the ratio of the wavelength 33 to the dimensions of the array.
34 In addition, as the separation between the planes is reduced to electrically small values, as 36 would often be necessary for conformal applications, 37 mutual coupling between the dipoles and transmission 38 lines is known to occur, thereby reducing the 39 reception and conversion efficiencies even further.
02 One approach to eliminating the prior art 03 requirement for polarization tracking equipment has 04 been to replace the linearly polarized dipole array 05 rectenna with a circularly polarized microstrip 06 antenna array, as described in U.S. Patent 07 4,079,~68. However, it is believed that such a 08 proposed microstrip antenna array would be incapable 09 of achieving the 85% or better reception efficiencies which are characteristic of linearly polarized 11 thin-film dipole rectennae.
12 SUMMARY OF THE INVE~TION
13 According to the present invention, a dual 14 polarization system is provided comprised of one or lS more pairs of orthogonally disposed rectennae and a 16 backplane, wherein each pair of rectennae is aligned 17 according to a specific and predetermined pattern and 18 separated by a predetermined distance, and the 19 respective pairs of rectennae are separated from the backplane by predetermined amounts in order to 21 compensate for the shielding effect of the 22 transmission lines.
23 More particularly, the transmission lines 24 and dipole antennae of each pair of rectennae are oriented such that lines parallel to and midway 26 between the transmission lines on a first one of the 27 rectenna foreplanes are aligned with lines parallel to 28 and midway between the dipoles on the other rectenna 29 foreplane. Conversely, lines perpendicular to and midway between the dipoles of the other rectenna 31 foreplane are aligned with lines parallel to and 32 overlying the dipoles of the first rectenna.
33 The system according to the present 34 invention is capable of receiving and converting a high fraction of the total power in an incident dual 36 polarization electromagnetic field irrespective of 37 polarization orientation movement between the 3~ transmitter and rectenna receiving system. The system 1 3Qq7~9 also e~hibits reduced signal reception ef~iciency losses as compared to prior art multiple foreplane s systems over a wide range of beam incidence angles.
Moreover, the system has twice ~he power handling capability per unit area of the prior art single linear rectenna array.
In accordance with an embodiment of the invention, an electromagnetic energy transmission, reception and conversion system is comprised of apparatus for generating and transmitting a beam of dual polarized electromagnetic waves, a moving vehicle, and a pair of parallel rectennae and a reflector screen mounted on the vehicle, for receiving and converting the beam of electromagnetic waves to electric power for use on the vehicle, the pair of rectennae being oriented with respect to each other according to a predetermined alignment and the reflector screen being separated from the pair of rectennae by predetermined amounts for cancelling mutual inductance between the pair of rectennae, resulting in high efficiency reception of the beam over a wide range of angles of incidence of the beam on the pair of rectennae.
In accordance with another embodiment of the invention, a first rectenna formed from a first plurality of dipole antenna elements connected to a first plurality of transmission lines orthogonal to the antenna elements, for receiving and carrying a first polarization component of the electro~agnetic waves, a second rectenna parallel to the first rectenna and formed from a second plurality of dipole antenna - elements oriented orthogonally to the first - 5a -plurality of antenna elements, and connected to a second plurali~y of transmission lines orthogonal to S the second plurality of antenna elements, for receiving and carrying a second polarization component of the electromagnetic waves orthogonal to the first component, a reflector plane parallel to the second rectenna for reflecting incident electromagnetic waves transmitted through the first and second rectennae back to the first and second rectennae for reception thereby, and the first and second rectennae being separated by a first predetermined distance, the second rectennae and reflector plane being separated by a second predetermined distance, and the first and second pluralities of dipole antenna elements and transmission lines conforming to a predetermined alignment with respect to each other for cancelling the effect of inductances in the first and second rectennae due to the second and first pluralities of transmission lines respectively, re~ulting in high efficiency reception Of the beam of dual polarized electromagnetic waves over a wide range of angles of incidence of the beam on the array.
In accordance with another embodiment of the invention, an antenna array for receiving dual polarized electromagnetic waves is comprised of a first plurality of thin-film printed circuit rectennae formed from a first plurality of linear half wavelength dipole antennae for receiving a first component of the electromagnetic waves, each of the rectennae of the first plurality being separated by a distance equivalent to a predetermined number of multiples of 1 3l~769 - 5~ -one half of the wavelength of the electromagnetic waves, a second plurality of thin-film printed circuit rectennae parallel to the first plurality of rectennae and formed from a second plurality of linear half wavelength dipole antennae for receiving a second component of the electromagnetic waves orthogonal to the first component, each of the rectennae of the second plurality being separated by a distance equivalent to the predetermined number of multiples of one half of the wavelength of the electromagnetic waves, a reflector screen parallel to the second plurality of rectennae, for reflecting incident electromagnetic waves transmitted through the first and second rectennae back to the first and second rectannae for reception thereby, and the first and second pluralities of rectennae being oriented with respect to each other according to a predetermined alignment and the reflector screen being separated from the first and second pluralities of rectennae by predetermined amounts for cancelling mutual inductance between the rectennae, resulting in high efficiency reception of the waves over a wide range of angles of incidence of the waves on the pair of rectennae.
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of the present invention will be obtained with reference to the detailed description below, in conjunction with the following drawings in which:
Figure lA is a perspective view of a microwave powered aircraft embodying the principles of the present invention, 1 3097~q - 5c -Fi~ure ls is a perspective view of a dual polarization electromagnetic power reception and conversion system configured in accordance with the present invention, with two foreplanes and one reflector backplane, Figure 2A is a plan view of a first one of the foreplanes illustrated in Figure lB, showing the orientation of linear dipoles in the X-direction, Figure 2B is a plan view of a second one of the foreplanes illustrated in Figure lB, showing the orientation of linear dipoles in the Y-direction, Figure 2C is a schematic transmission line network model representing the power reception and conversion systems illustrated in Figures lA, lB, 2A
and 2s, and Figure 3 is a perspective view of an alternative embodiment of the dual polarization electromagnetic power reception and conversion system according to the present invention, with multiple X and Y foreplanes.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning briefly to Figure lA, a microwave-powered aircraft V is shown in flight over a microwave 1 ~q769 02 transmitter TX . The aircraft ha~ a microwave power 03 receiver and converter A mounted on the aircraft V for 04 receiving microwave energy from the transmitter TX and 05 converting the received energy to useful power for 06 driving a propeller P (or other propulsion means) as 07 well as supplying payload power for operating on-board 08 equipment. Although Figure lA illustrates wing 09 mounted receiver/converters A, additional receivers can be mounted elsewhere on the aircraft for effecting 11 a larger power reception surface.
12 With reference to Figure lB, the dual 13 polarization electromagnetic power receiver and 14 converter of Figure lA is shown in accordance with the principles of the present invention in its most 16 general form. X and Y oriented rectenna foreplanes 1 17 and 2 respectively, are disposed in parallel with one 18 another for intercepting a portion of an 19 electromagnetic beam 3 transmitted perpendicular to the foreplanes 1 and 2.
21 According to the environment in which the 22 present invention operates, a transmitter antenna (Tx 23 in Figure lA) emits dual polarized waves, (i.e. waves 24 of two orthogonal polarizations) which can be unequal in either or both of amplitude and phase. This class 26 of transmitted waves includes the well known cases of 27 linearly and circularly polarized waves. Accordingly, 28 the two orthogonal field components of the incident 29 beam 3 can be resolved into components aligned into each of the two directions, X and Y.
31 As shown in Figure lB, the rectenna 32 foreplane 1 is comprised of an array of linearly-33 polarized half-wave dipole antenna elements 5A
34 oriented parallel to the X direction. Therefore, the dipole antenna elements 5A are capable of selectively 36 receiving the transmitted wavefield component which is 37 oriented in the X-direction.
02 The other orthogonal component of the 03 transmitte~ wavefield, which cannot be received on the 04 dipole elements 5A of foreplane 1, continues to 05 propagate through the foreplane 1 and is incident on 06 foreplane 2. The foreplane 2 is comprised of a second 07 thin-film printed circuit rectenna comprised of a 08 further array of linearly-polarized half-wave dipole 09 elements 5B, oriented parallel to the Y-direction.
Therefore, the additional dipole elements 5B can 11 selectively receive the orthogonal component of the 12 transmitted wavefield oriented in the Y-direction.
13 The dipole elements 5A and SB are connected 14 via transmission line busses 8A and 8B respectively, as discussed in greater detail below with reference to 16 Figures 2A, 2B and 2C. Also, the foreplane 1 is 17 separated from foreplane 2 by a distance of m~ /2, 18 where m is an integer value (including 0) and A is 19 the wavelength of the received microwave beam 3.
Furthermore, foreplane 2 is separated from reflector 21 plane 4 by a predetermined distance "p", as discussed 22 in greater detail below.
23 Turning to Figures 2A and 2B, the rectenna 24 foreplanes 1 and 2 are shown positioned relative to one another according to a predetermined pattern, 26 resulting in an increase in the overall dual 27 polarization power reception efficiency over prior art 28 multiple foreplane approaches.
29 In particular, Figure 2A illustrates the format and dimensions of the rectenna foreplane 1.
31 Half-wave dipole antenna elements 5A are oriented in 32 the X-direction and are configured in a repetitive 33 spaced array of spacing ~ , each dipole element 5A
34 being connected to wave filters 6A and rectifier circuits 7A, and to adjacent dipole elements 5A. The 36 transmission lines or busses 8A are disposed 37 orthogonal to the dipole elements, for collecting the 38 converted power from each element of the array.
02 Figure 2s illustrates the identical 03 components on the second rectenna foreplane 2.
04 The half-wave dipole an-tenna elements 5s are oriented 05 in the Y-direction. Thus, the arrangement on rectenna 06 foreplane 2 is the same as that on foreplane 1 except 07 that it is rotated 90 relative to foreplane 1.
08 Furthermore, the lines parallel to and midway between 09 the transmission lines 8B on foreplane 2, (denoted by lines of symmetry B'B' in Fig~lre 2B), are aligned with 11 the lines parallel to and midway between the dipole 12 elements 5A in foreplane 1 (denoted by lines of 13 symmetry B-B in E'igure 2A). Conversely, the lines 14 perpendicular and midway between respective rows of the dipole elements 5A in foreplane 1 (denoted by 16 lines of symmetry A-A in Figure 2A) are aligned with 17 the lines parallel to and along the dipole elements 5B
18 of foreplane 2, (denoted by lines of symmetry A'-A' in 19 Figure 2B).
In order to facilitate a better 21 understanding of the novel characteristics of the 22 present invention, the prior art concept of the 23 "independent transmission line cell" will be 24 explained. For a dual polarized beam, normally incident on the plane of a rectenna array (see Figure 26 1), it is well known that the electromagnetic boundary 27 conditions for each component of the two orthogonally
03 This invention relates in general to the 04 transfer of electrical power between two separated 05 locations by means of transmitting and receiving 06 electromagnetic waves, and more particularly to an 07 antenna array for receiving dual polarized electro-08 magnetic waves with high efficiency over a wide range 09 of angles of incidence.
Research in the area of remotely powered 11 mobile systems has centered around the requirement for12 cost effective means to receive and convert 13 transmitted electromagnetic power into direct current 14 power when the transmitter and receiver are moving relative to one another.
16 For example, it has been proposed that an 17 electromagnetic power recep-tion and conversion system18 could be implemented for transmitting propulsive and 19 communications payload power in the 2.4 - 2.5 GHz microwave ISM band to a lightweight electrically-21 powered aircraft circling over a fixed ground antenna 22 system for continuous periods of weeks or even months 23 at a time.
24 One prior art electromagnetic power reception and conversion system is described in U.S.
26 Patent 3,434,678, and is referred to as a linear 27 rectenna. This device consists of an array of 28 linearly polarized half-wavelength dipole antennae, 29 each followed by a conversion system consisting of wave filters and rectifier circuits.
31 In order to achieve high efficiency power 32 collection with the linearly polarized rectenna 33 described in the prior art patent, the transmitted 34 electromagnetic field must itself be linearly polarized. In addition, the polarization orientation 36 of this field must be maintained parallel to that of 37 the rectenna dipoles, or vice versa, in response to 38 changes in the orientation of the receiving rectenna ~' - .
1 30q76q 02 relative to the power transmission antenna, or due to 03 Faraday rotation of a polarized beam transmitted 04 through the ionosphere, etc. In other words, 05 expensive and complex polarization tracking equipment 06 must be provided at either the transmitting antenna or 07 the receiving rectenna in order for the system to 08 operate properly with high efEiciency power 09 collection.
An improvement in linearly polarized 11 rectennae is described in an article entitled "Design 12 Definition of a Microwave Power Reception and 13 Conversion System for Use on a High Altitude Powered 14 Platform" NASA/CR/156866, by W.C. ~rown, published in 1981. According to the Brown article, a linearly 16 polariæed rectenna is disclosed in the form of a 17 thin-film printed circuit. This type of linear 18 rectenna has many desirable characteristics which were 19 not possessed by earlier prior art rectennae constructed of discrete components; such as those 21 described in a further article of W.C. srown entitled 22 "The History Of The Development Of The ~ectenna", 23 publication of the S.P.S. Microwave Systems Workshop, 24 Rectenna Session, Lyndon B. Johnson Space Center, Houston, Texas, January 15-18, 1980.
26 With the exception of the inclusion of 27 rectifier diodes, all components of the improved 28 rectenna were etched on a sing]e thin-film dielectric 29 sheet. Therefore, when compared with earlier discrete component rectennae, the potential fabrication costs 31 for volume production are very low. Furthermore, the 32 structural weight of the thin-film rectenna is very 33 low (eg. typically less than 100 grams-per-square-34 meter), and the thin-film fabrication is very flexible and can be conformed to curved surfaces such as 36 aircraft wings, etc.
37 However, the improved rectenna disclosed by 38 W.C. Brown also suffers from the principle 1 3aq76s 01 ~ 3 ~
02 disadvantage oE well known prior art discrete 03 componen-t rectennae, which is that for high efficiency 04 power reception the polarization orientation of the 05 field should be parallel to that of the rectenna 06 dipoles, resulting in the necessity of expensive and 07 complex polarization tracking equipment.
08 A further prior art system is described in Og U.S. Patent 3,681,769 which teaches the use of multiple phased arrays of orthogonal dipoles disposed 11 on separate planes and interconnected via transmission 12 lines for transmission of radio signals in a dual 13 polarized beam.
14 However, this prior art approach suffers lS from poor efficiency performance due to shielding 16 effects caused by the transmission lines. As an 17 example, when two thin-film rectennae of the type and 18 dimensions described in the latter mentioned article 19 by Brown are laid out in two orthogonal foreplanes as taught by U.S. Patent 3,681,769, it can be readily 21 shown that approximately 30-40~ of the power in one 22 polarization is prevented from being received by the 23 transmission lines of the other foreplane.
24 Furthermore, such phased arrays of orthogonally disposed dipoles are subject to extremely poor 26 directivity when applied to systems in which the angle 27 of beam incidence varies (e.g. in systems 28 characterized by relative movement between the 29 transmitting and receiving stations, such as in an electrically propelled airborne transportation 31 system). This is because the directivity of such 32 arrays is proportional to the ratio of the wavelength 33 to the dimensions of the array.
34 In addition, as the separation between the planes is reduced to electrically small values, as 36 would often be necessary for conformal applications, 37 mutual coupling between the dipoles and transmission 38 lines is known to occur, thereby reducing the 39 reception and conversion efficiencies even further.
02 One approach to eliminating the prior art 03 requirement for polarization tracking equipment has 04 been to replace the linearly polarized dipole array 05 rectenna with a circularly polarized microstrip 06 antenna array, as described in U.S. Patent 07 4,079,~68. However, it is believed that such a 08 proposed microstrip antenna array would be incapable 09 of achieving the 85% or better reception efficiencies which are characteristic of linearly polarized 11 thin-film dipole rectennae.
12 SUMMARY OF THE INVE~TION
13 According to the present invention, a dual 14 polarization system is provided comprised of one or lS more pairs of orthogonally disposed rectennae and a 16 backplane, wherein each pair of rectennae is aligned 17 according to a specific and predetermined pattern and 18 separated by a predetermined distance, and the 19 respective pairs of rectennae are separated from the backplane by predetermined amounts in order to 21 compensate for the shielding effect of the 22 transmission lines.
23 More particularly, the transmission lines 24 and dipole antennae of each pair of rectennae are oriented such that lines parallel to and midway 26 between the transmission lines on a first one of the 27 rectenna foreplanes are aligned with lines parallel to 28 and midway between the dipoles on the other rectenna 29 foreplane. Conversely, lines perpendicular to and midway between the dipoles of the other rectenna 31 foreplane are aligned with lines parallel to and 32 overlying the dipoles of the first rectenna.
33 The system according to the present 34 invention is capable of receiving and converting a high fraction of the total power in an incident dual 36 polarization electromagnetic field irrespective of 37 polarization orientation movement between the 3~ transmitter and rectenna receiving system. The system 1 3Qq7~9 also e~hibits reduced signal reception ef~iciency losses as compared to prior art multiple foreplane s systems over a wide range of beam incidence angles.
Moreover, the system has twice ~he power handling capability per unit area of the prior art single linear rectenna array.
In accordance with an embodiment of the invention, an electromagnetic energy transmission, reception and conversion system is comprised of apparatus for generating and transmitting a beam of dual polarized electromagnetic waves, a moving vehicle, and a pair of parallel rectennae and a reflector screen mounted on the vehicle, for receiving and converting the beam of electromagnetic waves to electric power for use on the vehicle, the pair of rectennae being oriented with respect to each other according to a predetermined alignment and the reflector screen being separated from the pair of rectennae by predetermined amounts for cancelling mutual inductance between the pair of rectennae, resulting in high efficiency reception of the beam over a wide range of angles of incidence of the beam on the pair of rectennae.
In accordance with another embodiment of the invention, a first rectenna formed from a first plurality of dipole antenna elements connected to a first plurality of transmission lines orthogonal to the antenna elements, for receiving and carrying a first polarization component of the electro~agnetic waves, a second rectenna parallel to the first rectenna and formed from a second plurality of dipole antenna - elements oriented orthogonally to the first - 5a -plurality of antenna elements, and connected to a second plurali~y of transmission lines orthogonal to S the second plurality of antenna elements, for receiving and carrying a second polarization component of the electromagnetic waves orthogonal to the first component, a reflector plane parallel to the second rectenna for reflecting incident electromagnetic waves transmitted through the first and second rectennae back to the first and second rectennae for reception thereby, and the first and second rectennae being separated by a first predetermined distance, the second rectennae and reflector plane being separated by a second predetermined distance, and the first and second pluralities of dipole antenna elements and transmission lines conforming to a predetermined alignment with respect to each other for cancelling the effect of inductances in the first and second rectennae due to the second and first pluralities of transmission lines respectively, re~ulting in high efficiency reception Of the beam of dual polarized electromagnetic waves over a wide range of angles of incidence of the beam on the array.
In accordance with another embodiment of the invention, an antenna array for receiving dual polarized electromagnetic waves is comprised of a first plurality of thin-film printed circuit rectennae formed from a first plurality of linear half wavelength dipole antennae for receiving a first component of the electromagnetic waves, each of the rectennae of the first plurality being separated by a distance equivalent to a predetermined number of multiples of 1 3l~769 - 5~ -one half of the wavelength of the electromagnetic waves, a second plurality of thin-film printed circuit rectennae parallel to the first plurality of rectennae and formed from a second plurality of linear half wavelength dipole antennae for receiving a second component of the electromagnetic waves orthogonal to the first component, each of the rectennae of the second plurality being separated by a distance equivalent to the predetermined number of multiples of one half of the wavelength of the electromagnetic waves, a reflector screen parallel to the second plurality of rectennae, for reflecting incident electromagnetic waves transmitted through the first and second rectennae back to the first and second rectannae for reception thereby, and the first and second pluralities of rectennae being oriented with respect to each other according to a predetermined alignment and the reflector screen being separated from the first and second pluralities of rectennae by predetermined amounts for cancelling mutual inductance between the rectennae, resulting in high efficiency reception of the waves over a wide range of angles of incidence of the waves on the pair of rectennae.
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of the present invention will be obtained with reference to the detailed description below, in conjunction with the following drawings in which:
Figure lA is a perspective view of a microwave powered aircraft embodying the principles of the present invention, 1 3097~q - 5c -Fi~ure ls is a perspective view of a dual polarization electromagnetic power reception and conversion system configured in accordance with the present invention, with two foreplanes and one reflector backplane, Figure 2A is a plan view of a first one of the foreplanes illustrated in Figure lB, showing the orientation of linear dipoles in the X-direction, Figure 2B is a plan view of a second one of the foreplanes illustrated in Figure lB, showing the orientation of linear dipoles in the Y-direction, Figure 2C is a schematic transmission line network model representing the power reception and conversion systems illustrated in Figures lA, lB, 2A
and 2s, and Figure 3 is a perspective view of an alternative embodiment of the dual polarization electromagnetic power reception and conversion system according to the present invention, with multiple X and Y foreplanes.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning briefly to Figure lA, a microwave-powered aircraft V is shown in flight over a microwave 1 ~q769 02 transmitter TX . The aircraft ha~ a microwave power 03 receiver and converter A mounted on the aircraft V for 04 receiving microwave energy from the transmitter TX and 05 converting the received energy to useful power for 06 driving a propeller P (or other propulsion means) as 07 well as supplying payload power for operating on-board 08 equipment. Although Figure lA illustrates wing 09 mounted receiver/converters A, additional receivers can be mounted elsewhere on the aircraft for effecting 11 a larger power reception surface.
12 With reference to Figure lB, the dual 13 polarization electromagnetic power receiver and 14 converter of Figure lA is shown in accordance with the principles of the present invention in its most 16 general form. X and Y oriented rectenna foreplanes 1 17 and 2 respectively, are disposed in parallel with one 18 another for intercepting a portion of an 19 electromagnetic beam 3 transmitted perpendicular to the foreplanes 1 and 2.
21 According to the environment in which the 22 present invention operates, a transmitter antenna (Tx 23 in Figure lA) emits dual polarized waves, (i.e. waves 24 of two orthogonal polarizations) which can be unequal in either or both of amplitude and phase. This class 26 of transmitted waves includes the well known cases of 27 linearly and circularly polarized waves. Accordingly, 28 the two orthogonal field components of the incident 29 beam 3 can be resolved into components aligned into each of the two directions, X and Y.
31 As shown in Figure lB, the rectenna 32 foreplane 1 is comprised of an array of linearly-33 polarized half-wave dipole antenna elements 5A
34 oriented parallel to the X direction. Therefore, the dipole antenna elements 5A are capable of selectively 36 receiving the transmitted wavefield component which is 37 oriented in the X-direction.
02 The other orthogonal component of the 03 transmitte~ wavefield, which cannot be received on the 04 dipole elements 5A of foreplane 1, continues to 05 propagate through the foreplane 1 and is incident on 06 foreplane 2. The foreplane 2 is comprised of a second 07 thin-film printed circuit rectenna comprised of a 08 further array of linearly-polarized half-wave dipole 09 elements 5B, oriented parallel to the Y-direction.
Therefore, the additional dipole elements 5B can 11 selectively receive the orthogonal component of the 12 transmitted wavefield oriented in the Y-direction.
13 The dipole elements 5A and SB are connected 14 via transmission line busses 8A and 8B respectively, as discussed in greater detail below with reference to 16 Figures 2A, 2B and 2C. Also, the foreplane 1 is 17 separated from foreplane 2 by a distance of m~ /2, 18 where m is an integer value (including 0) and A is 19 the wavelength of the received microwave beam 3.
Furthermore, foreplane 2 is separated from reflector 21 plane 4 by a predetermined distance "p", as discussed 22 in greater detail below.
23 Turning to Figures 2A and 2B, the rectenna 24 foreplanes 1 and 2 are shown positioned relative to one another according to a predetermined pattern, 26 resulting in an increase in the overall dual 27 polarization power reception efficiency over prior art 28 multiple foreplane approaches.
29 In particular, Figure 2A illustrates the format and dimensions of the rectenna foreplane 1.
31 Half-wave dipole antenna elements 5A are oriented in 32 the X-direction and are configured in a repetitive 33 spaced array of spacing ~ , each dipole element 5A
34 being connected to wave filters 6A and rectifier circuits 7A, and to adjacent dipole elements 5A. The 36 transmission lines or busses 8A are disposed 37 orthogonal to the dipole elements, for collecting the 38 converted power from each element of the array.
02 Figure 2s illustrates the identical 03 components on the second rectenna foreplane 2.
04 The half-wave dipole an-tenna elements 5s are oriented 05 in the Y-direction. Thus, the arrangement on rectenna 06 foreplane 2 is the same as that on foreplane 1 except 07 that it is rotated 90 relative to foreplane 1.
08 Furthermore, the lines parallel to and midway between 09 the transmission lines 8B on foreplane 2, (denoted by lines of symmetry B'B' in Fig~lre 2B), are aligned with 11 the lines parallel to and midway between the dipole 12 elements 5A in foreplane 1 (denoted by lines of 13 symmetry B-B in E'igure 2A). Conversely, the lines 14 perpendicular and midway between respective rows of the dipole elements 5A in foreplane 1 (denoted by 16 lines of symmetry A-A in Figure 2A) are aligned with 17 the lines parallel to and along the dipole elements 5B
18 of foreplane 2, (denoted by lines of symmetry A'-A' in 19 Figure 2B).
In order to facilitate a better 21 understanding of the novel characteristics of the 22 present invention, the prior art concept of the 23 "independent transmission line cell" will be 24 explained. For a dual polarized beam, normally incident on the plane of a rectenna array (see Figure 26 1), it is well known that the electromagnetic boundary 27 conditions for each component of the two orthogonally
2~ polarized waves are not affected by the existence of 29 idealized magnetic and electric walls erected along predetermined planes of symmetry perpendicular to the 31 rectenna foreplanes.
32 For example, the x-polarized plane wave is 33 characterized by electric walls constructed on planes 34 located at one half _he distance between adjacent pairs of transmission lines, (eg. passing through 36 lines A-A and A'A' in Figures 2A and 2B, 37 respectively), and magnetic walls constructed on 38 planes located at one half the distance between 1 30q76q 02 adjacent parallel dipole elements (e.g. through lines 03 B-B and B's' in Figures 2A and 2s, respectively).
04 These imaginary electric and magnetic walls 05 extending in front and behind the foreplanes 1 and 2 06 define identical transmission line cells enclosing 07 each dipole element of the arrays. It has been 08 determined mathematically that when considering the 09 electromagnetic boundary conditions for orthogonally 10 polarized waves, the field outside of the cell may be 11 completely ignored and the array behavior determined 12 from the behavior of a single transmission line cell, 13 such as that represented by the hatched areas of 14 Figures 2A and 2B, for the x-polarized component of 15 the received wave. In other words, all mutual 16 coupling due to neighbouring elements is automatically 17 taken into account by the specific configuration of 18 the foreplanes 1 and 2.
19 From Figure 2B it is seen that, according to 20 the specific configuration of the present invention, 21 the dipole elements 5B lie along the aforementioned 22 electric walls and therefore do not affect the 23 transmission line characteristics. The rectenna 24 transmission lines 8B also appear as purely inductive 25 strips across the electric walls of the cell.
26 Similar cells can be constructed for 27 analyzing the characteristics of the Y-polarized wave.
28 By considering the configuration of 29 foreplanes 1 and 2 according to the above-described 30 concept of the independent cell, a series of 31 foreplanes and reflectors can be equated for 32 analytical purposes with a series of electric network 33 elements connected by free space transmission lines as 34 shown in Figure 2C, whereby all of the electromagnetic 35 field considerations of the rectenna structure can be 36 translated and reduced to a simple electric network 37 problem.
02 Specifically, with reference to Figure 2C, 03 for the X-polarization, a transmission line cell 04 becomes a transmission line lOa carrying power from a 05 distant X-polarization microwave transmitter 12a.
06 This transmission line lOa is shunted at foreplane 1 07 by rectenna dipole elements 5A (terminated with a 08 linear load), shunted at foreplane 2 by the 09 transmission lines 8B which lie across the electric 10 walls, and terminated by reflector plane 4 at a 11 distance "p" from the foreplane 2 (see also Figure 12 lB). The characteristic impedance ZO represents the 13 impedance of the transmission line lOa in free space-14 Similarly, for the Y-polarization, the transmission line cell becomes a transmission line lOb 16 carrying power from a distant Y-polarization ~icrowave 17 transmitter 12b and is shunted at foreplane 2 by 18 dipole elements 5s and at foreplane 1 by inductive 19 transmission lines 8A, and terminated by the reflector plane 4 forming a short circuit connection.
21 It is then a standard networ~ problem to 22 show that when the two foreplanes 1 and 2 are 23 separated by a distance of m ~/2, where m may take any 24 integer value, the effect of the foreplane transmission lines 8A and 8B may effectively be 26 compensated for. This is accomplished by adjusting 27 the reflector spacing "p" (Figure 1) to capacitively 28 balance the effect of the inductive strips at the 29 rectenna foreplanes (i.e. the capacitive reactance of the short circuited transmission lines lOa and lOb at 31 reflector plane 4 is made equal and opposite to the 32 inductive reactance caused by the transmission lines 33 8A and 8B such that all of the power in the 34 transmission lines 8A and 8B is absorbed by the matched antenna load). It should be noted that "m"
36 may take the value zero (i.e. for conformal 37 applications), provided electrical isolation between 38 the foreplanes 1 and 2 is maintained.
~ 30~76q 02 To confirm that the above-described objects 03 of the invention have been met, tests were carried out 04 using circularly-polarized transmitted waves. It was 05 found out that a successful prototype of the 06 embodiment of the present invention resulted in a 07 reception efficiency degraded by less than 5% below 08 that which could be obtained with a single 09 linearly-polarized thin-film rectenna constructed 10 according to prior art. However, according to the 11 present invention, no expensive and complex 12 polarization tracking equipment was required to 13 maintain high efficiency reception in the event of 14 rotational movement between the transmitter and 15 receiver.
16 Moreover, a successful prototype of the 17 present invention has been incorporated into the 18 world's first microwave powered aircraft which has now 19 completed many test flights under rigorous 20 conditions. All test flights have established the 21 utility of the invention as well as the proven 22 feasibility of remotely powered moving systems.
23 A person understanding the present invention 24 may conceive of other embodiments or variations 25 therein. For example, whereas the disclosed 26 embodiments relate to rectenna arrays having a square 27 layout, existing prior art rectangular or triangular 28 dipole element layouts may be reconfigured in 29 a square layout embodying the principles of the 30 present invention. Also, the restriction on foreplane 31 separation may be eliminated if separate reflector 32 grids are used for each polarization.
33 The theory of operation of the present 34 invention described above with reference to Figures 35 lB, 2A and 2B considered only the case of a beam 36 normally incident on an array. However, in accordance 37 with an important feature of the present invention, 38 the method of compensation described above is 1 3097~
02 applicable to any specified angle of incidence, 03 suitable modiEications being made to the transmission 04 line cell characteristic impedance and lengths in 05 Fi~ure 2C.
06 The specified angle is usually chosen ~o be 07 that which is ~ost desirable for matching the antenna 08 to its power conversion circuit over the operational 09 range of beam incidence, and it (though not the polarization orientation) can often be strictly 11 controlled, in order to maintain the impedance 12 stability necessary for total energy absorption. Due 13 to the analogy between an off-broadside angle of 14 incidence and an inclined transmission line cell, the effect of the inductive strips may still be 16 compensated for and the transmitted power received by 17 the matched antenna load.
18 In cases where the range of beam incidence 19 cannot be carefully limited (e.g. banking of the aircraft V relative to the microwave beam in Figure 21 lA, or movement of the reception system over long 22 distances,) the variation in rectenna reception 23 efficiency due to varying angles of beam incidence is 24 reduced according to the transmission line compensation scheme of the present invention, with 26 suitable selection of foreplane separation and 27 reflector spacing.
28 For example, for a dual polarization 29 rectenna of foreplane separation 0.08 ~ and a reflector plane 4 located 0.23 ~ behind foreplane 2, 31 the efficiency of power reception has been computed to 32 vary from 96~ to 80% as the angle of beam incidence 33 varies from 0 to + 50 from broadside. This may be 34 compared to a change in efficiency of from 100~ to 67 for prior art rectennae, over the same variation in 36 angle of beam incidence.
1 3097h9 02 Hence, power transmission wavefields can be 03 received according to the present invention over a 04 wide range of incidence angles.
05 Furthermore, once the dual polarization 06 system is formulated in network terms according to the 07 con-figuration oE the present invention, the effect of 08 changes or modifications to the system may be 09 quantified and compensated for according to the aforementioned network model. For example, dielectric 11 material may be inserted above or between the 12 respective foreplanes for mechanical considerations, 13 resulting in changes in the characteristic impedance 14 ZO above and between the foreplanes. Also in certain applications the required DC power from a rectenna 16 system may be more than can be handled by two 17 foreplanes. Therefore, as shown in Figure 3, multiple 18 foreplanes (l, lA...lN, 2, 2A...2N) for each 19 polarization (separated by a multiple of half wavelengths), can be arranged to share the power 21 absorbed in each polarization direction. However, the 22 parallel conversion circuit impedances must be chosen 23 to match the transmission line cell impedance as 24 discussed above.
Moreover, although the successful prototype 26 of the present invention utili~ed a microwave power 27 transmission, reception and conversion system, it is 28 contemplated that systems could be developed using the 29 principles of the present invention applied to power conversion of electromagnetic energy in other 31 frequency bands (e.g. radio, laser, etc.~.
32 Also, whereas the successful prototype of 33 the invention was implemented on a microwave powered 34 aircraft, it is contemplated that the principles of the present invention may be applied to developing 36 other land, air, sea or space-based transportation 37 systems, or providing payload power to remote 38 equipment, (e.g. high-powered radar, microwave 39 repeater platforms, on-board sensors, etc.).
1 ~f;Jf~7b~i 02 These and other modifications or variations 03 are believed to be within the sphere and scope of the 04 present invention as defined in the claims appended 05 hereto.
32 For example, the x-polarized plane wave is 33 characterized by electric walls constructed on planes 34 located at one half _he distance between adjacent pairs of transmission lines, (eg. passing through 36 lines A-A and A'A' in Figures 2A and 2B, 37 respectively), and magnetic walls constructed on 38 planes located at one half the distance between 1 30q76q 02 adjacent parallel dipole elements (e.g. through lines 03 B-B and B's' in Figures 2A and 2s, respectively).
04 These imaginary electric and magnetic walls 05 extending in front and behind the foreplanes 1 and 2 06 define identical transmission line cells enclosing 07 each dipole element of the arrays. It has been 08 determined mathematically that when considering the 09 electromagnetic boundary conditions for orthogonally 10 polarized waves, the field outside of the cell may be 11 completely ignored and the array behavior determined 12 from the behavior of a single transmission line cell, 13 such as that represented by the hatched areas of 14 Figures 2A and 2B, for the x-polarized component of 15 the received wave. In other words, all mutual 16 coupling due to neighbouring elements is automatically 17 taken into account by the specific configuration of 18 the foreplanes 1 and 2.
19 From Figure 2B it is seen that, according to 20 the specific configuration of the present invention, 21 the dipole elements 5B lie along the aforementioned 22 electric walls and therefore do not affect the 23 transmission line characteristics. The rectenna 24 transmission lines 8B also appear as purely inductive 25 strips across the electric walls of the cell.
26 Similar cells can be constructed for 27 analyzing the characteristics of the Y-polarized wave.
28 By considering the configuration of 29 foreplanes 1 and 2 according to the above-described 30 concept of the independent cell, a series of 31 foreplanes and reflectors can be equated for 32 analytical purposes with a series of electric network 33 elements connected by free space transmission lines as 34 shown in Figure 2C, whereby all of the electromagnetic 35 field considerations of the rectenna structure can be 36 translated and reduced to a simple electric network 37 problem.
02 Specifically, with reference to Figure 2C, 03 for the X-polarization, a transmission line cell 04 becomes a transmission line lOa carrying power from a 05 distant X-polarization microwave transmitter 12a.
06 This transmission line lOa is shunted at foreplane 1 07 by rectenna dipole elements 5A (terminated with a 08 linear load), shunted at foreplane 2 by the 09 transmission lines 8B which lie across the electric 10 walls, and terminated by reflector plane 4 at a 11 distance "p" from the foreplane 2 (see also Figure 12 lB). The characteristic impedance ZO represents the 13 impedance of the transmission line lOa in free space-14 Similarly, for the Y-polarization, the transmission line cell becomes a transmission line lOb 16 carrying power from a distant Y-polarization ~icrowave 17 transmitter 12b and is shunted at foreplane 2 by 18 dipole elements 5s and at foreplane 1 by inductive 19 transmission lines 8A, and terminated by the reflector plane 4 forming a short circuit connection.
21 It is then a standard networ~ problem to 22 show that when the two foreplanes 1 and 2 are 23 separated by a distance of m ~/2, where m may take any 24 integer value, the effect of the foreplane transmission lines 8A and 8B may effectively be 26 compensated for. This is accomplished by adjusting 27 the reflector spacing "p" (Figure 1) to capacitively 28 balance the effect of the inductive strips at the 29 rectenna foreplanes (i.e. the capacitive reactance of the short circuited transmission lines lOa and lOb at 31 reflector plane 4 is made equal and opposite to the 32 inductive reactance caused by the transmission lines 33 8A and 8B such that all of the power in the 34 transmission lines 8A and 8B is absorbed by the matched antenna load). It should be noted that "m"
36 may take the value zero (i.e. for conformal 37 applications), provided electrical isolation between 38 the foreplanes 1 and 2 is maintained.
~ 30~76q 02 To confirm that the above-described objects 03 of the invention have been met, tests were carried out 04 using circularly-polarized transmitted waves. It was 05 found out that a successful prototype of the 06 embodiment of the present invention resulted in a 07 reception efficiency degraded by less than 5% below 08 that which could be obtained with a single 09 linearly-polarized thin-film rectenna constructed 10 according to prior art. However, according to the 11 present invention, no expensive and complex 12 polarization tracking equipment was required to 13 maintain high efficiency reception in the event of 14 rotational movement between the transmitter and 15 receiver.
16 Moreover, a successful prototype of the 17 present invention has been incorporated into the 18 world's first microwave powered aircraft which has now 19 completed many test flights under rigorous 20 conditions. All test flights have established the 21 utility of the invention as well as the proven 22 feasibility of remotely powered moving systems.
23 A person understanding the present invention 24 may conceive of other embodiments or variations 25 therein. For example, whereas the disclosed 26 embodiments relate to rectenna arrays having a square 27 layout, existing prior art rectangular or triangular 28 dipole element layouts may be reconfigured in 29 a square layout embodying the principles of the 30 present invention. Also, the restriction on foreplane 31 separation may be eliminated if separate reflector 32 grids are used for each polarization.
33 The theory of operation of the present 34 invention described above with reference to Figures 35 lB, 2A and 2B considered only the case of a beam 36 normally incident on an array. However, in accordance 37 with an important feature of the present invention, 38 the method of compensation described above is 1 3097~
02 applicable to any specified angle of incidence, 03 suitable modiEications being made to the transmission 04 line cell characteristic impedance and lengths in 05 Fi~ure 2C.
06 The specified angle is usually chosen ~o be 07 that which is ~ost desirable for matching the antenna 08 to its power conversion circuit over the operational 09 range of beam incidence, and it (though not the polarization orientation) can often be strictly 11 controlled, in order to maintain the impedance 12 stability necessary for total energy absorption. Due 13 to the analogy between an off-broadside angle of 14 incidence and an inclined transmission line cell, the effect of the inductive strips may still be 16 compensated for and the transmitted power received by 17 the matched antenna load.
18 In cases where the range of beam incidence 19 cannot be carefully limited (e.g. banking of the aircraft V relative to the microwave beam in Figure 21 lA, or movement of the reception system over long 22 distances,) the variation in rectenna reception 23 efficiency due to varying angles of beam incidence is 24 reduced according to the transmission line compensation scheme of the present invention, with 26 suitable selection of foreplane separation and 27 reflector spacing.
28 For example, for a dual polarization 29 rectenna of foreplane separation 0.08 ~ and a reflector plane 4 located 0.23 ~ behind foreplane 2, 31 the efficiency of power reception has been computed to 32 vary from 96~ to 80% as the angle of beam incidence 33 varies from 0 to + 50 from broadside. This may be 34 compared to a change in efficiency of from 100~ to 67 for prior art rectennae, over the same variation in 36 angle of beam incidence.
1 3097h9 02 Hence, power transmission wavefields can be 03 received according to the present invention over a 04 wide range of incidence angles.
05 Furthermore, once the dual polarization 06 system is formulated in network terms according to the 07 con-figuration oE the present invention, the effect of 08 changes or modifications to the system may be 09 quantified and compensated for according to the aforementioned network model. For example, dielectric 11 material may be inserted above or between the 12 respective foreplanes for mechanical considerations, 13 resulting in changes in the characteristic impedance 14 ZO above and between the foreplanes. Also in certain applications the required DC power from a rectenna 16 system may be more than can be handled by two 17 foreplanes. Therefore, as shown in Figure 3, multiple 18 foreplanes (l, lA...lN, 2, 2A...2N) for each 19 polarization (separated by a multiple of half wavelengths), can be arranged to share the power 21 absorbed in each polarization direction. However, the 22 parallel conversion circuit impedances must be chosen 23 to match the transmission line cell impedance as 24 discussed above.
Moreover, although the successful prototype 26 of the present invention utili~ed a microwave power 27 transmission, reception and conversion system, it is 28 contemplated that systems could be developed using the 29 principles of the present invention applied to power conversion of electromagnetic energy in other 31 frequency bands (e.g. radio, laser, etc.~.
32 Also, whereas the successful prototype of 33 the invention was implemented on a microwave powered 34 aircraft, it is contemplated that the principles of the present invention may be applied to developing 36 other land, air, sea or space-based transportation 37 systems, or providing payload power to remote 38 equipment, (e.g. high-powered radar, microwave 39 repeater platforms, on-board sensors, etc.).
1 ~f;Jf~7b~i 02 These and other modifications or variations 03 are believed to be within the sphere and scope of the 04 present invention as defined in the claims appended 05 hereto.
Claims (18)
1. An antenna array for receiving a beam of dual polarized electromagnetic waves, comprised of:
a) a first rectenna formed from a first plurality of dipole antenna elements connected to a first plurality of transmission lines orthogonal to said antenna elements, for receiving and carrying a first polarization component of said electromagnetic waves, b) a second rectenna parallel to said first rectenna and formed from a second plurality of dipole antenna elements oriented orthogonally to said first plurality of antenna elements, and connected to a second plurality of transmission lines orthogonal to said second plurality of antenna elements, for receiving and carrying a second polarization component of said electromagnetic waves orthogonal to said first component, c) a reflector plane parallel to said second rectenna for reflecting incident electromagnetic waves transmitted through said first and second rectennae back to said first and second rectennae for reception thereby, and d) said first and second rectennae being separated by a first predetermined distance, said second rectennae and reflector plane being separated by a second predetermined distance, and said first and second pluralities of dipole antenna elements and transmission lines conforming to a predetermined alignment with respect to each other for cancelling the effect of inductances in said first and second rectennae due to said second and first pluralities of transmission lines respectively, resulting in high efficiency reception of said beam of dual polarized electromagnetic waves over a wide range of angles of incidence of said beam on said array.
a) a first rectenna formed from a first plurality of dipole antenna elements connected to a first plurality of transmission lines orthogonal to said antenna elements, for receiving and carrying a first polarization component of said electromagnetic waves, b) a second rectenna parallel to said first rectenna and formed from a second plurality of dipole antenna elements oriented orthogonally to said first plurality of antenna elements, and connected to a second plurality of transmission lines orthogonal to said second plurality of antenna elements, for receiving and carrying a second polarization component of said electromagnetic waves orthogonal to said first component, c) a reflector plane parallel to said second rectenna for reflecting incident electromagnetic waves transmitted through said first and second rectennae back to said first and second rectennae for reception thereby, and d) said first and second rectennae being separated by a first predetermined distance, said second rectennae and reflector plane being separated by a second predetermined distance, and said first and second pluralities of dipole antenna elements and transmission lines conforming to a predetermined alignment with respect to each other for cancelling the effect of inductances in said first and second rectennae due to said second and first pluralities of transmission lines respectively, resulting in high efficiency reception of said beam of dual polarized electromagnetic waves over a wide range of angles of incidence of said beam on said array.
2. An antenna array as defined in claim 1, wherein each of said first and second thin-film printed circuit rectennae is further comprised of:
(a) a plurality of wave filters connected to said transmission lines, for filtering said received first and second components of said electromagnetic wave carried by said busses; and (b) a plurality of rectifier diodes connected to said transmission lines and said wave filters, for rectifying said received and filtered components carried by said transmission lines, and in response generating an output power signal.
(a) a plurality of wave filters connected to said transmission lines, for filtering said received first and second components of said electromagnetic wave carried by said busses; and (b) a plurality of rectifier diodes connected to said transmission lines and said wave filters, for rectifying said received and filtered components carried by said transmission lines, and in response generating an output power signal.
3. An antenna array as defined in claim 2, wherein said predetermined alignment is such that respective first lines disposed mid-point between respective rows of said transmission lines of the first rectenna are colinear when viewed along said beam with respective dipole antenna elements on said second rectenna, and further lines disposed orthogonal to said first lines and passing midway between successive ones of said dipole antennae of the first rectenna are parallel to and midway between respective rows of transmission lines of said second rectenna when viewed along said beam whereby said first and further lines intersect to form a plurality of independent transmission line cells enclosing respective pairs of said dipole antennae of said first rectenna, such that directivity of said array is characterized by the directivity of each of said cells, resulting in high efficiency reception of said electromagnetic waves over a wide range of beam incidence angles.
4. An antenna array as defined in claim 1, wherein said first and second rectennae and said reflector plane are separated by predetermined amounts sufficient to capacitively balance any inductance caused by said transmission lines.
5. An antenna array as defined in claim 1, wherein the distance separating said first and second rectennae is given by = , where m is a whole number and .lambda. is the wavelength of said electromagnetic wave.
6. An antenna array as defined in claim 5, wherein m=0, and electrical isolation is provided between said first and second rectennae, thereby enabling conformal application of said rectennae to a curved surface.
7. An antenna array for receiving dual polarized electromagnetic waves comprised of:
a) a first plurality of thin-film printed circuit rectennae formed from a first plurality of linear half wavelength dipole antennae for receiving a first component of said electromagnetic waves, each of said rectennae of said first plurality being separated by a distance equivalent to a predetermined number of multiples of one half of the wavelength of said electromagnetic waves, b) a second plurality of thin-film printed circuit rectennae parallel to said first plurality of rectennae and formed from a second plurality of linear half wavelength dipole antennae for receiving a second component of said electromagnetic waves orthogonal to said first component, each of said rectennae of said second plurality being separated by a distance equivalent to said predetermined number of multiples of one half of the wavelength of said electromagnetic waves, c) a reflector screen parallel to said second plurality of rectennae, for reflecting incident electromagnetic waves transmitted through said first and second rectennae back to said first and second rectennae for reception thereby, and d) said first and second pluralities of rectennae being oriented with respect to each other according to a predetermined alignment and said reflector screen being separated from said first and second pluralities of rectennae by predetermined amounts for cancelling mutual inductance between said rectennae, resulting in high efficiency reception of said waves over a wide range of angles of incidence of said waves on said pair of rectennae.
a) a first plurality of thin-film printed circuit rectennae formed from a first plurality of linear half wavelength dipole antennae for receiving a first component of said electromagnetic waves, each of said rectennae of said first plurality being separated by a distance equivalent to a predetermined number of multiples of one half of the wavelength of said electromagnetic waves, b) a second plurality of thin-film printed circuit rectennae parallel to said first plurality of rectennae and formed from a second plurality of linear half wavelength dipole antennae for receiving a second component of said electromagnetic waves orthogonal to said first component, each of said rectennae of said second plurality being separated by a distance equivalent to said predetermined number of multiples of one half of the wavelength of said electromagnetic waves, c) a reflector screen parallel to said second plurality of rectennae, for reflecting incident electromagnetic waves transmitted through said first and second rectennae back to said first and second rectennae for reception thereby, and d) said first and second pluralities of rectennae being oriented with respect to each other according to a predetermined alignment and said reflector screen being separated from said first and second pluralities of rectennae by predetermined amounts for cancelling mutual inductance between said rectennae, resulting in high efficiency reception of said waves over a wide range of angles of incidence of said waves on said pair of rectennae.
8. An electromagnetic energy transmission, reception and conversion system, comprised of:
a) means for generating and transmitting a beam of dual polarized electromagnetic waves, b) a moving vehicle, and c) a pair of parallel rectennae and a reflector screen mounted on said vehicle, for receiving and converting said beam of electromagnetic waves to electric power for use on said vehicle, said pair of rectennae being oriented with respect to each other according to a predetermined alignment and said reflector screen being separated from said pair of rectennae by predetermined amounts for cancelling mutual inductance between said pair of rectennae, resulting in high efficiency reception of said beam over a wide range of angles of incidence of said beam on said pair of rectennae.
a) means for generating and transmitting a beam of dual polarized electromagnetic waves, b) a moving vehicle, and c) a pair of parallel rectennae and a reflector screen mounted on said vehicle, for receiving and converting said beam of electromagnetic waves to electric power for use on said vehicle, said pair of rectennae being oriented with respect to each other according to a predetermined alignment and said reflector screen being separated from said pair of rectennae by predetermined amounts for cancelling mutual inductance between said pair of rectennae, resulting in high efficiency reception of said beam over a wide range of angles of incidence of said beam on said pair of rectennae.
9. An electromagnetic energy transmission, reception and conversion system as defined in claim 8, wherein said means for generating and transmitting said beam of dual polarized electromagnetic waves is comprised of a microwave transmitter.
10. An electromagnetic energy transmission, reception and conversion system as defined in claim 8, wherein said vehicle is an aircraft with said rectennae being mounted on an undersurface thereof, means being provided on said aircraft for receiving said electric power and in response propelling said aircraft.
11. An electromagnetic energy transmission, reception and conversion system as defined in claim 10, wherein said rectennae and said reflector screen are conformally applied to the undersurface of respective wings of said aircraft.
12. An electromagnetic energy transmission, reception and conversion system as defined in claim 8, wherein said pair of rectennae are separate by a distance of m .lambda./2, where m is a whole number and .lambda. is the wavelength of said electromagnetic waves.
13. An electromagnetic energy transmission, reception and conversion system as defined in claim 9, wherein said pair of rectennae are separate by a distance of m .lambda./2 where m is a whole number and .lambda. is the wavelength of said electromagnetic waves.
14. An electromagnetic energy transmission, reception and conversion mobile system as defined in claim 10, wherein said pair of rectennae are separate by a distance of m .lambda./2, where m is a whole number and .lambda. is the wavelength of said electromagnetic waves.
15. An electromagnetic energy transmission, reception and conversion mobile system as defined in claim 8, wherein each said pair of rectennae are comprised of a plurality of D.C. power collection transmission lines interconnecting a plurality of dipole antenna elements, and a plurality of wave filters and rectifiers for filtering and rectifying said received beam and in response generating said electric power.
16. An electromagnetic energy transmission, reception and conversion system as defined in claim 15, wherein said plurality of dipole antenna elements and D.C. power collection transmission lines are arranged in a square array.
17. An electromagnetic energy transmission, reception and conversion system as defined in claim 16, wherein said predetermined alignment of said pair of rectennae comprises alignment of a first plurality of lines parallel to and midway between said transmission lines on a first one of said rectennae with a second plurality of lines parallel to and midway between said dipole antenna elements of the other of said rectennae, and alignment of a third plurality of lines perpendicular to and midway between said dipole antenna elements of said other rectenna with a fourth plurality of lines parallel to and colinear with the dipole antenna elements of said first rectennae.
18. An electromagnetic energy transmission, reception and conversion system as defined in claim 8, wherein said vehicle further includes electrically powered payload, said electric power being applied to operation of said payload.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US124,159 | 1987-11-23 | ||
| US07/124,159 US4943811A (en) | 1987-11-23 | 1987-11-23 | Dual polarization electromagnetic power reception and conversion system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1309769C true CA1309769C (en) | 1992-11-03 |
Family
ID=22413143
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000577680A Expired - Fee Related CA1309769C (en) | 1987-11-23 | 1988-09-16 | Dual polarization electromagnetic power reception and conversion system |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4943811A (en) |
| EP (1) | EP0325034A3 (en) |
| JP (1) | JPH01202127A (en) |
| CA (1) | CA1309769C (en) |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8307922B2 (en) | 2005-05-24 | 2012-11-13 | Rearden, Llc | System and method for powering an aircraft using radio frequency signals and feedback |
| US8469122B2 (en) | 2005-05-24 | 2013-06-25 | Rearden, Llc | System and method for powering vehicle using radio frequency signals and feedback |
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| US5503350A (en) * | 1993-10-28 | 1996-04-02 | Skysat Communications Network Corporation | Microwave-powered aircraft |
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| US20070017718A1 (en) * | 2005-07-20 | 2007-01-25 | Chrobak Dennis S | Power systems for transportation and residential uses |
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| FR2901061B1 (en) * | 2006-05-12 | 2008-11-14 | Centre Nat Rech Scient | ELECTROMAGNETIC WAVE CONVERTER IN CONTINUOUS VOLTAGE |
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| US9331390B2 (en) * | 2014-03-26 | 2016-05-03 | Laird Technologies, Inc. | Antenna assemblies |
| JP5975359B2 (en) * | 2014-04-23 | 2016-08-23 | パナソニックＩｐマネジメント株式会社 | Wireless power feeding method and wireless power feeding system |
| TWI583060B (en) * | 2014-12-29 | 2017-05-11 | Merry Electronics Co Ltd | Coupling antenna |
| US10862197B2 (en) | 2016-06-27 | 2020-12-08 | The Regents Of The University Of California | Monopole rectenna arrays distributed over a curved surface for multi-directional, multi-polarization, and multi-band ambient RF energy harvesting |
| CN108631044B (en) * | 2017-03-16 | 2020-07-31 | 启碁科技股份有限公司 | Antenna system and wireless network base station |
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| US3681769A (en) * | 1970-07-30 | 1972-08-01 | Itt | Dual polarized printed circuit dipole antenna array |
| US3887925A (en) * | 1973-07-31 | 1975-06-03 | Itt | Linearly polarized phased antenna array |
| US4079268A (en) * | 1976-10-06 | 1978-03-14 | Nasa | Thin conformal antenna array for microwave power conversion |
| JPS55111633A (en) * | 1979-02-20 | 1980-08-28 | Nippon Electric Co | Rectenna device |
| JPS57107610A (en) * | 1980-12-25 | 1982-07-05 | Nippon Telegr & Teleph Corp <Ntt> | Circular polarized wave cone beam antenna |
| FR2523376A1 (en) * | 1982-03-12 | 1983-09-16 | Labo Electronique Physique | RADIATION ELEMENT OR HYPERFREQUENCY SIGNAL RECEIVER WITH LEFT AND RIGHT CIRCULAR POLARIZATIONS AND FLAT ANTENNA COMPRISING A NETWORK OF SUCH JUXTAPOSED ELEMENTS |
| SU1094110A1 (en) * | 1983-02-01 | 1984-05-23 | Предприятие П/Я А-1836 | Rectenna |
-
1987
- 1987-11-23 US US07/124,159 patent/US4943811A/en not_active Expired - Lifetime
-
1988
- 1988-09-16 CA CA000577680A patent/CA1309769C/en not_active Expired - Fee Related
- 1988-11-22 JP JP63295887A patent/JPH01202127A/en active Pending
- 1988-11-23 EP EP88311092A patent/EP0325034A3/en not_active Ceased
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| US10277290B2 (en) | 2004-04-02 | 2019-04-30 | Rearden, Llc | Systems and methods to exploit areas of coherence in wireless systems |
| US10333604B2 (en) | 2004-04-02 | 2019-06-25 | Rearden, Llc | System and method for distributed antenna wireless communications |
| US9819403B2 (en) | 2004-04-02 | 2017-11-14 | Rearden, Llc | System and method for managing handoff of a client between different distributed-input-distributed-output (DIDO) networks based on detected velocity of the client |
| US9826537B2 (en) | 2004-04-02 | 2017-11-21 | Rearden, Llc | System and method for managing inter-cluster handoff of clients which traverse multiple DIDO clusters |
| US10425134B2 (en) | 2004-04-02 | 2019-09-24 | Rearden, Llc | System and methods for planned evolution and obsolescence of multiuser spectrum |
| US8307922B2 (en) | 2005-05-24 | 2012-11-13 | Rearden, Llc | System and method for powering an aircraft using radio frequency signals and feedback |
| US8469122B2 (en) | 2005-05-24 | 2013-06-25 | Rearden, Llc | System and method for powering vehicle using radio frequency signals and feedback |
| US9973246B2 (en) | 2013-03-12 | 2018-05-15 | Rearden, Llc | Systems and methods for exploiting inter-cell multiplexing gain in wireless cellular systems via distributed input distributed output technology |
| US10488535B2 (en) | 2013-03-12 | 2019-11-26 | Rearden, Llc | Apparatus and method for capturing still images and video using diffraction coded imaging techniques |
| US9923657B2 (en) | 2013-03-12 | 2018-03-20 | Rearden, Llc | Systems and methods for exploiting inter-cell multiplexing gain in wireless cellular systems via distributed input distributed output technology |
| US11451281B2 (en) | 2013-03-12 | 2022-09-20 | Rearden, Llc | Systems and methods for exploiting inter-cell multiplexing gain in wireless cellular systems via distributed input distributed output technology |
| US10547358B2 (en) | 2013-03-15 | 2020-01-28 | Rearden, Llc | Systems and methods for radio frequency calibration exploiting channel reciprocity in distributed input distributed output wireless communications |
| US11146313B2 (en) | 2013-03-15 | 2021-10-12 | Rearden, Llc | Systems and methods for radio frequency calibration exploiting channel reciprocity in distributed input distributed output wireless communications |
| US11189917B2 (en) | 2014-04-16 | 2021-11-30 | Rearden, Llc | Systems and methods for distributing radioheads |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01202127A (en) | 1989-08-15 |
| EP0325034A3 (en) | 1989-08-09 |
| US4943811A (en) | 1990-07-24 |
| EP0325034A2 (en) | 1989-07-26 |
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